[test] traversal: Separate traversal tests (#9574)

Authored by: Grub4K

test/test_traversal.py

@@ -0,0 +1,379 @@
+import re
+import xml.etree.ElementTree
+
+import pytest
+
+from yt_dlp.utils import dict_get, int_or_none, str_or_none
+from yt_dlp.utils.traversal import traverse_obj
+
+_TEST_DATA = {
+    100: 100,
+    1.2: 1.2,
+    'str': 'str',
+    'None': None,
+    '...': ...,
+    'urls': [
+        {'index': 0, 'url': 'https://www.example.com/0'},
+        {'index': 1, 'url': 'https://www.example.com/1'},
+    ],
+    'data': (
+        {'index': 2},
+        {'index': 3},
+    ),
+    'dict': {},
+}
+
+
+class TestTraversal:
+    def test_dict_get(self):
+        FALSE_VALUES = {
+            'none': None,
+            'false': False,
+            'zero': 0,
+            'empty_string': '',
+            'empty_list': [],
+        }
+        d = {**FALSE_VALUES, 'a': 42}
+        assert dict_get(d, 'a') == 42
+        assert dict_get(d, 'b') is None
+        assert dict_get(d, 'b', 42) == 42
+        assert dict_get(d, ('a',)) == 42
+        assert dict_get(d, ('b', 'a')) == 42
+        assert dict_get(d, ('b', 'c', 'a', 'd')) == 42
+        assert dict_get(d, ('b', 'c')) is None
+        assert dict_get(d, ('b', 'c'), 42) == 42
+        for key, false_value in FALSE_VALUES.items():
+            assert dict_get(d, ('b', 'c', key)) is None
+            assert dict_get(d, ('b', 'c', key), skip_false_values=False) == false_value
+
+    def test_traversal_base(self):
+        assert traverse_obj(_TEST_DATA, ('str',)) == 'str', \
+            'allow tuple path'
+        assert traverse_obj(_TEST_DATA, ['str']) == 'str', \
+            'allow list path'
+        assert traverse_obj(_TEST_DATA, (value for value in ("str",))) == 'str', \
+            'allow iterable path'
+        assert traverse_obj(_TEST_DATA, 'str') == 'str', \
+            'single items should be treated as a path'
+        assert traverse_obj(_TEST_DATA, 100) == 100, \
+            'allow int path'
+        assert traverse_obj(_TEST_DATA, 1.2) == 1.2, \
+            'allow float path'
+        assert traverse_obj(_TEST_DATA, None) == _TEST_DATA, \
+            '`None` should not perform any modification'
+
+    def test_traversal_ellipsis(self):
+        assert traverse_obj(_TEST_DATA, ...) == [x for x in _TEST_DATA.values() if x not in (None, {})], \
+            '`...` should give all non discarded values'
+        assert traverse_obj(_TEST_DATA, ('urls', 0, ...)) == list(_TEST_DATA['urls'][0].values()), \
+            '`...` selection for dicts should select all values'
+        assert traverse_obj(_TEST_DATA, (..., ..., 'url')) == ['https://www.example.com/0', 'https://www.example.com/1'], \
+            'nested `...` queries should work'
+        assert traverse_obj(_TEST_DATA, (..., ..., 'index')) == list(range(4)), \
+            '`...` query result should be flattened'
+        assert traverse_obj(iter(range(4)), ...) == list(range(4)), \
+            '`...` should accept iterables'
+
+    def test_traversal_function(self):
+        filter_func = lambda x, y: x == 'urls' and isinstance(y, list)
+        assert traverse_obj(_TEST_DATA, filter_func) == [_TEST_DATA['urls']], \
+            'function as query key should perform a filter based on (key, value)'
+        assert traverse_obj(_TEST_DATA, lambda _, x: isinstance(x[0], str)) == ['str'], \
+            'exceptions in the query function should be catched'
+        assert traverse_obj(iter(range(4)), lambda _, x: x % 2 == 0) == [0, 2], \
+            'function key should accept iterables'
+        # Wrong function signature should raise (debug mode)
+        with pytest.raises(Exception):
+            traverse_obj(_TEST_DATA, lambda a: ...)
+        with pytest.raises(Exception):
+            traverse_obj(_TEST_DATA, lambda a, b, c: ...)
+
+    def test_traversal_set(self):
+        # transformation/type, like `expected_type`
+        assert traverse_obj(_TEST_DATA, (..., {str.upper}, )) == ['STR'], \
+            'Function in set should be a transformation'
+        assert traverse_obj(_TEST_DATA, (..., {str})) == ['str'], \
+            'Type in set should be a type filter'
+        assert traverse_obj(_TEST_DATA, {dict}) == _TEST_DATA, \
+            'A single set should be wrapped into a path'
+        assert traverse_obj(_TEST_DATA, (..., {str.upper})) == ['STR'], \
+            'Transformation function should not raise'
+        expected = [x for x in map(str_or_none, _TEST_DATA.values()) if x is not None]
+        assert traverse_obj(_TEST_DATA, (..., {str_or_none})) == expected, \
+            'Function in set should be a transformation'
+        assert traverse_obj(_TEST_DATA, ('fail', {lambda _: 'const'})) == 'const', \
+            'Function in set should always be called'
+        # Sets with length != 1 should raise in debug
+        with pytest.raises(Exception):
+            traverse_obj(_TEST_DATA, set())
+        with pytest.raises(Exception):
+            traverse_obj(_TEST_DATA, {str.upper, str})
+
+    def test_traversal_slice(self):
+        _SLICE_DATA = [0, 1, 2, 3, 4]
+
+        assert traverse_obj(_TEST_DATA, ('dict', slice(1))) is None, \
+            'slice on a dictionary should not throw'
+        assert traverse_obj(_SLICE_DATA, slice(1)) == _SLICE_DATA[:1], \
+            'slice key should apply slice to sequence'
+        assert traverse_obj(_SLICE_DATA, slice(1, 2)) == _SLICE_DATA[1:2], \
+            'slice key should apply slice to sequence'
+        assert traverse_obj(_SLICE_DATA, slice(1, 4, 2)) == _SLICE_DATA[1:4:2], \
+            'slice key should apply slice to sequence'
+
+    def test_traversal_alternatives(self):
+        assert traverse_obj(_TEST_DATA, 'fail', 'str') == 'str', \
+            'multiple `paths` should be treated as alternative paths'
+        assert traverse_obj(_TEST_DATA, 'str', 100) == 'str', \
+            'alternatives should exit early'
+        assert traverse_obj(_TEST_DATA, 'fail', 'fail') is None, \
+            'alternatives should return `default` if exhausted'
+        assert traverse_obj(_TEST_DATA, (..., 'fail'), 100) == 100, \
+            'alternatives should track their own branching return'
+        assert traverse_obj(_TEST_DATA, ('dict', ...), ('data', ...)) == list(_TEST_DATA['data']), \
+            'alternatives on empty objects should search further'
+
+    def test_traversal_branching_nesting(self):
+        assert traverse_obj(_TEST_DATA, ('urls', (3, 0), 'url')) == ['https://www.example.com/0'], \
+            'tuple as key should be treated as branches'
+        assert traverse_obj(_TEST_DATA, ('urls', [3, 0], 'url')) == ['https://www.example.com/0'], \
+            'list as key should be treated as branches'
+        assert traverse_obj(_TEST_DATA, ('urls', ((1, 'fail'), (0, 'url')))) == ['https://www.example.com/0'], \
+            'double nesting in path should be treated as paths'
+        assert traverse_obj(['0', [1, 2]], [(0, 1), 0]) == [1], \
+            'do not fail early on branching'
+        expected = ['https://www.example.com/0', 'https://www.example.com/1']
+        assert traverse_obj(_TEST_DATA, ('urls', ((0, ('fail', 'url')), (1, 'url')))) == expected, \
+            'tripple nesting in path should be treated as branches'
+        assert traverse_obj(_TEST_DATA, ('urls', ('fail', (..., 'url')))) == expected, \
+            'ellipsis as branch path start gets flattened'
+
+    def test_traversal_dict(self):
+        assert traverse_obj(_TEST_DATA, {0: 100, 1: 1.2}) == {0: 100, 1: 1.2}, \
+            'dict key should result in a dict with the same keys'
+        expected = {0: 'https://www.example.com/0'}
+        assert traverse_obj(_TEST_DATA, {0: ('urls', 0, 'url')}) == expected, \
+            'dict key should allow paths'
+        expected = {0: ['https://www.example.com/0']}
+        assert traverse_obj(_TEST_DATA, {0: ('urls', (3, 0), 'url')}) == expected, \
+            'tuple in dict path should be treated as branches'
+        assert traverse_obj(_TEST_DATA, {0: ('urls', ((1, 'fail'), (0, 'url')))}) == expected, \
+            'double nesting in dict path should be treated as paths'
+        expected = {0: ['https://www.example.com/1', 'https://www.example.com/0']}
+        assert traverse_obj(_TEST_DATA, {0: ('urls', ((1, ('fail', 'url')), (0, 'url')))}) == expected, \
+            'tripple nesting in dict path should be treated as branches'
+        assert traverse_obj(_TEST_DATA, {0: 'fail'}) == {}, \
+            'remove `None` values when top level dict key fails'
+        assert traverse_obj(_TEST_DATA, {0: 'fail'}, default=...) == {0: ...}, \
+            'use `default` if key fails and `default`'
+        assert traverse_obj(_TEST_DATA, {0: 'dict'}) == {}, \
+            'remove empty values when dict key'
+        assert traverse_obj(_TEST_DATA, {0: 'dict'}, default=...) == {0: ...}, \
+            'use `default` when dict key and `default`'
+        assert traverse_obj(_TEST_DATA, {0: {0: 'fail'}}) == {}, \
+            'remove empty values when nested dict key fails'
+        assert traverse_obj(None, {0: 'fail'}) == {}, \
+            'default to dict if pruned'
+        assert traverse_obj(None, {0: 'fail'}, default=...) == {0: ...}, \
+            'default to dict if pruned and default is given'
+        assert traverse_obj(_TEST_DATA, {0: {0: 'fail'}}, default=...) == {0: {0: ...}}, \
+            'use nested `default` when nested dict key fails and `default`'
+        assert traverse_obj(_TEST_DATA, {0: ('dict', ...)}) == {}, \
+            'remove key if branch in dict key not successful'
+
+    def test_traversal_default(self):
+        _DEFAULT_DATA = {'None': None, 'int': 0, 'list': []}
+
+        assert traverse_obj(_DEFAULT_DATA, 'fail') is None, \
+            'default value should be `None`'
+        assert traverse_obj(_DEFAULT_DATA, 'fail', 'fail', default=...) == ..., \
+            'chained fails should result in default'
+        assert traverse_obj(_DEFAULT_DATA, 'None', 'int') == 0, \
+            'should not short cirquit on `None`'
+        assert traverse_obj(_DEFAULT_DATA, 'fail', default=1) == 1, \
+            'invalid dict key should result in `default`'
+        assert traverse_obj(_DEFAULT_DATA, 'None', default=1) == 1, \
+            '`None` is a deliberate sentinel and should become `default`'
+        assert traverse_obj(_DEFAULT_DATA, ('list', 10)) is None, \
+            '`IndexError` should result in `default`'
+        assert traverse_obj(_DEFAULT_DATA, (..., 'fail'), default=1) == 1, \
+            'if branched but not successful return `default` if defined, not `[]`'
+        assert traverse_obj(_DEFAULT_DATA, (..., 'fail'), default=None) is None, \
+            'if branched but not successful return `default` even if `default` is `None`'
+        assert traverse_obj(_DEFAULT_DATA, (..., 'fail')) == [], \
+            'if branched but not successful return `[]`, not `default`'
+        assert traverse_obj(_DEFAULT_DATA, ('list', ...)) == [], \
+            'if branched but object is empty return `[]`, not `default`'
+        assert traverse_obj(None, ...) == [], \
+            'if branched but object is `None` return `[]`, not `default`'
+        assert traverse_obj({0: None}, (0, ...)) == [], \
+            'if branched but state is `None` return `[]`, not `default`'
+
+    @pytest.mark.parametrize('path', [
+        ('fail', ...),
+        (..., 'fail'),
+        100 * ('fail',) + (...,),
+        (...,) + 100 * ('fail',),
+    ])
+    def test_traversal_branching(self, path):
+        assert traverse_obj({}, path) == [], \
+            'if branched but state is `None`, return `[]` (not `default`)'
+        assert traverse_obj({}, 'fail', path) == [], \
+            'if branching in last alternative and previous did not match, return `[]` (not `default`)'
+        assert traverse_obj({0: 'x'}, 0, path) == 'x', \
+            'if branching in last alternative and previous did match, return single value'
+        assert traverse_obj({0: 'x'}, path, 0) == 'x', \
+            'if branching in first alternative and non-branching path does match, return single value'
+        assert traverse_obj({}, path, 'fail') is None, \
+            'if branching in first alternative and non-branching path does not match, return `default`'
+
+    def test_traversal_expected_type(self):
+        _EXPECTED_TYPE_DATA = {'str': 'str', 'int': 0}
+
+        assert traverse_obj(_EXPECTED_TYPE_DATA, 'str', expected_type=str) == 'str', \
+            'accept matching `expected_type` type'
+        assert traverse_obj(_EXPECTED_TYPE_DATA, 'str', expected_type=int) is None, \
+            'reject non matching `expected_type` type'
+        assert traverse_obj(_EXPECTED_TYPE_DATA, 'int', expected_type=lambda x: str(x)) == '0', \
+            'transform type using type function'
+        assert traverse_obj(_EXPECTED_TYPE_DATA, 'str', expected_type=lambda _: 1 / 0) is None, \
+            'wrap expected_type fuction in try_call'
+        assert traverse_obj(_EXPECTED_TYPE_DATA, ..., expected_type=str) == ['str'], \
+            'eliminate items that expected_type fails on'
+        assert traverse_obj(_TEST_DATA, {0: 100, 1: 1.2}, expected_type=int) == {0: 100}, \
+            'type as expected_type should filter dict values'
+        assert traverse_obj(_TEST_DATA, {0: 100, 1: 1.2, 2: 'None'}, expected_type=str_or_none) == {0: '100', 1: '1.2'}, \
+            'function as expected_type should transform dict values'
+        assert traverse_obj(_TEST_DATA, ({0: 1.2}, 0, {int_or_none}), expected_type=int) == 1, \
+            'expected_type should not filter non final dict values'
+        assert traverse_obj(_TEST_DATA, {0: {0: 100, 1: 'str'}}, expected_type=int) == {0: {0: 100}}, \
+            'expected_type should transform deep dict values'
+        assert traverse_obj(_TEST_DATA, [({0: '...'}, {0: '...'})], expected_type=type(...)) == [{0: ...}, {0: ...}], \
+            'expected_type should transform branched dict values'
+        assert traverse_obj({1: {3: 4}}, [(1, 2), 3], expected_type=int) == [4], \
+            'expected_type regression for type matching in tuple branching'
+        assert traverse_obj(_TEST_DATA, ['data', ...], expected_type=int) == [], \
+            'expected_type regression for type matching in dict result'
+
+    def test_traversal_get_all(self):
+        _GET_ALL_DATA = {'key': [0, 1, 2]}
+
+        assert traverse_obj(_GET_ALL_DATA, ('key', ...), get_all=False) == 0, \
+            'if not `get_all`, return only first matching value'
+        assert traverse_obj(_GET_ALL_DATA, ..., get_all=False) == [0, 1, 2], \
+            'do not overflatten if not `get_all`'
+
+    def test_traversal_casesense(self):
+        _CASESENSE_DATA = {
+            'KeY': 'value0',
+            0: {
+                'KeY': 'value1',
+                0: {'KeY': 'value2'},
+            },
+        }
+
+        assert traverse_obj(_CASESENSE_DATA, 'key') is None, \
+            'dict keys should be case sensitive unless `casesense`'
+        assert traverse_obj(_CASESENSE_DATA, 'keY', casesense=False) == 'value0', \
+            'allow non matching key case if `casesense`'
+        assert traverse_obj(_CASESENSE_DATA, [0, ('keY',)], casesense=False) == ['value1'], \
+            'allow non matching key case in branch if `casesense`'
+        assert traverse_obj(_CASESENSE_DATA, [0, ([0, 'keY'],)], casesense=False) == ['value2'], \
+            'allow non matching key case in branch path if `casesense`'
+
+    def test_traversal_traverse_string(self):
+        _TRAVERSE_STRING_DATA = {'str': 'str', 1.2: 1.2}
+
+        assert traverse_obj(_TRAVERSE_STRING_DATA, ('str', 0)) is None, \
+            'do not traverse into string if not `traverse_string`'
+        assert traverse_obj(_TRAVERSE_STRING_DATA, ('str', 0), traverse_string=True) == 's', \
+            'traverse into string if `traverse_string`'
+        assert traverse_obj(_TRAVERSE_STRING_DATA, (1.2, 1), traverse_string=True) == '.', \
+            'traverse into converted data if `traverse_string`'
+        assert traverse_obj(_TRAVERSE_STRING_DATA, ('str', ...), traverse_string=True) == 'str', \
+            '`...` should result in string (same value) if `traverse_string`'
+        assert traverse_obj(_TRAVERSE_STRING_DATA, ('str', slice(0, None, 2)), traverse_string=True) == 'sr', \
+            '`slice` should result in string if `traverse_string`'
+        assert traverse_obj(_TRAVERSE_STRING_DATA, ('str', lambda i, v: i or v == "s"), traverse_string=True) == 'str', \
+            'function should result in string if `traverse_string`'
+        assert traverse_obj(_TRAVERSE_STRING_DATA, ('str', (0, 2)), traverse_string=True) == ['s', 'r'], \
+            'branching should result in list if `traverse_string`'
+        assert traverse_obj({}, (0, ...), traverse_string=True) == [], \
+            'branching should result in list if `traverse_string`'
+        assert traverse_obj({}, (0, lambda x, y: True), traverse_string=True) == [], \
+            'branching should result in list if `traverse_string`'
+        assert traverse_obj({}, (0, slice(1)), traverse_string=True) == [], \
+            'branching should result in list if `traverse_string`'
+
+    def test_traversal_re(self):
+        mobj = re.fullmatch(r'0(12)(?P<group>3)(4)?', '0123')
+        assert traverse_obj(mobj, ...) == [x for x in mobj.groups() if x is not None], \
+            '`...` on a `re.Match` should give its `groups()`'
+        assert traverse_obj(mobj, lambda k, _: k in (0, 2)) == ['0123', '3'], \
+            'function on a `re.Match` should give groupno, value starting at 0'
+        assert traverse_obj(mobj, 'group') == '3', \
+            'str key on a `re.Match` should give group with that name'
+        assert traverse_obj(mobj, 2) == '3', \
+            'int key on a `re.Match` should give group with that name'
+        assert traverse_obj(mobj, 'gRoUp', casesense=False) == '3', \
+            'str key on a `re.Match` should respect casesense'
+        assert traverse_obj(mobj, 'fail') is None, \
+            'failing str key on a `re.Match` should return `default`'
+        assert traverse_obj(mobj, 'gRoUpS', casesense=False) is None, \
+            'failing str key on a `re.Match` should return `default`'
+        assert traverse_obj(mobj, 8) is None, \
+            'failing int key on a `re.Match` should return `default`'
+        assert traverse_obj(mobj, lambda k, _: k in (0, 'group')) == ['0123', '3'], \
+            'function on a `re.Match` should give group name as well'
+
+    def test_traversal_xml_etree(self):
+        etree = xml.etree.ElementTree.fromstring('''<?xml version="1.0"?>
+        <data>
+            <country name="Liechtenstein">
+                <rank>1</rank>
+                <year>2008</year>
+                <gdppc>141100</gdppc>
+                <neighbor name="Austria" direction="E"/>
+                <neighbor name="Switzerland" direction="W"/>
+            </country>
+            <country name="Singapore">
+                <rank>4</rank>
+                <year>2011</year>
+                <gdppc>59900</gdppc>
+                <neighbor name="Malaysia" direction="N"/>
+            </country>
+            <country name="Panama">
+                <rank>68</rank>
+                <year>2011</year>
+                <gdppc>13600</gdppc>
+                <neighbor name="Costa Rica" direction="W"/>
+                <neighbor name="Colombia" direction="E"/>
+            </country>
+        </data>''')
+        assert traverse_obj(etree, '') == etree, \
+            'empty str key should return the element itself'
+        assert traverse_obj(etree, 'country') == list(etree), \
+            'str key should lead all children with that tag name'
+        assert traverse_obj(etree, ...) == list(etree), \
+            '`...` as key should return all children'
+        assert traverse_obj(etree, lambda _, x: x[0].text == '4') == [etree[1]], \
+            'function as key should get element as value'
+        assert traverse_obj(etree, lambda i, _: i == 1) == [etree[1]], \
+            'function as key should get index as key'
+        assert traverse_obj(etree, 0) == etree[0], \
+            'int key should return the nth child'
+        expected = ['Austria', 'Switzerland', 'Malaysia', 'Costa Rica', 'Colombia']
+        assert traverse_obj(etree, './/neighbor/@name') == expected, \
+            '`@<attribute>` at end of path should give that attribute'
+        assert traverse_obj(etree, '//neighbor/@fail') == [None, None, None, None, None], \
+            '`@<nonexistant>` at end of path should give `None`'
+        assert traverse_obj(etree, ('//neighbor/@', 2)) == {'name': 'Malaysia', 'direction': 'N'}, \
+            '`@` should give the full attribute dict'
+        assert traverse_obj(etree, '//year/text()') == ['2008', '2011', '2011'], \
+            '`text()` at end of path should give the inner text'
+        assert traverse_obj(etree, '//*[@direction]/@direction') == ['E', 'W', 'N', 'W', 'E'], \
+            'full Python xpath features should be supported'
+        assert traverse_obj(etree, (0, '@name')) == 'Liechtenstein', \
+            'special transformations should act on current element'
+        assert traverse_obj(etree, ('country', 0, ..., 'text()', {int_or_none})) == [1, 2008, 141100], \
+            'special transformations should act on current element'

test/test_utils.py

@@ -2,7 +2,6 @@
 
 # Allow direct execution
 import os
-import re
 import sys
 import unittest
 import warnings
@@ -45,7 +44,6 @@
     determine_ext,
     determine_file_encoding,
     dfxp2srt,
-    dict_get,
     encode_base_n,
     encode_compat_str,
     encodeFilename,
@@ -106,13 +104,11 @@
     sanitize_url,
     shell_quote,
     smuggle_url,
-    str_or_none,
     str_to_int,
     strip_jsonp,
     strip_or_none,
     subtitles_filename,
     timeconvert,
-    traverse_obj,
     try_call,
     unescapeHTML,
     unified_strdate,
@@ -755,28 +751,6 @@ def test_multipart_encode(self):
         self.assertRaises(
             ValueError, multipart_encode, {b'field': b'value'}, boundary='value')
 
-    def test_dict_get(self):
-        FALSE_VALUES = {
-            'none': None,
-            'false': False,
-            'zero': 0,
-            'empty_string': '',
-            'empty_list': [],
-        }
-        d = FALSE_VALUES.copy()
-        d['a'] = 42
-        self.assertEqual(dict_get(d, 'a'), 42)
-        self.assertEqual(dict_get(d, 'b'), None)
-        self.assertEqual(dict_get(d, 'b', 42), 42)
-        self.assertEqual(dict_get(d, ('a', )), 42)
-        self.assertEqual(dict_get(d, ('b', 'a', )), 42)
-        self.assertEqual(dict_get(d, ('b', 'c', 'a', 'd', )), 42)
-        self.assertEqual(dict_get(d, ('b', 'c', )), None)
-        self.assertEqual(dict_get(d, ('b', 'c', ), 42), 42)
-        for key, false_value in FALSE_VALUES.items():
-            self.assertEqual(dict_get(d, ('b', 'c', key, )), None)
-            self.assertEqual(dict_get(d, ('b', 'c', key, ), skip_false_values=False), false_value)
-
     def test_merge_dicts(self):
         self.assertEqual(merge_dicts({'a': 1}, {'b': 2}), {'a': 1, 'b': 2})
         self.assertEqual(merge_dicts({'a': 1}, {'a': 2}), {'a': 1})
@@ -2039,359 +2013,6 @@ def test_variadic(self):
             warnings.simplefilter('ignore')
             self.assertEqual(variadic('spam', allowed_types=[dict]), 'spam')
 
-    def test_traverse_obj(self):
-        _TEST_DATA = {
-            100: 100,
-            1.2: 1.2,
-            'str': 'str',
-            'None': None,
-            '...': ...,
-            'urls': [
-                {'index': 0, 'url': 'https://www.example.com/0'},
-                {'index': 1, 'url': 'https://www.example.com/1'},
-            ],
-            'data': (
-                {'index': 2},
-                {'index': 3},
-            ),
-            'dict': {},
-        }
-
-        # Test base functionality
-        self.assertEqual(traverse_obj(_TEST_DATA, ('str',)), 'str',
-                         msg='allow tuple path')
-        self.assertEqual(traverse_obj(_TEST_DATA, ['str']), 'str',
-                         msg='allow list path')
-        self.assertEqual(traverse_obj(_TEST_DATA, (value for value in ("str",))), 'str',
-                         msg='allow iterable path')
-        self.assertEqual(traverse_obj(_TEST_DATA, 'str'), 'str',
-                         msg='single items should be treated as a path')
-        self.assertEqual(traverse_obj(_TEST_DATA, None), _TEST_DATA)
-        self.assertEqual(traverse_obj(_TEST_DATA, 100), 100)
-        self.assertEqual(traverse_obj(_TEST_DATA, 1.2), 1.2)
-
-        # Test Ellipsis behavior
-        self.assertCountEqual(traverse_obj(_TEST_DATA, ...),
-                              (item for item in _TEST_DATA.values() if item not in (None, {})),
-                              msg='`...` should give all non discarded values')
-        self.assertCountEqual(traverse_obj(_TEST_DATA, ('urls', 0, ...)), _TEST_DATA['urls'][0].values(),
-                              msg='`...` selection for dicts should select all values')
-        self.assertEqual(traverse_obj(_TEST_DATA, (..., ..., 'url')),
-                         ['https://www.example.com/0', 'https://www.example.com/1'],
-                         msg='nested `...` queries should work')
-        self.assertCountEqual(traverse_obj(_TEST_DATA, (..., ..., 'index')), range(4),
-                              msg='`...` query result should be flattened')
-        self.assertEqual(traverse_obj(iter(range(4)), ...), list(range(4)),
-                         msg='`...` should accept iterables')
-
-        # Test function as key
-        self.assertEqual(traverse_obj(_TEST_DATA, lambda x, y: x == 'urls' and isinstance(y, list)),
-                         [_TEST_DATA['urls']],
-                         msg='function as query key should perform a filter based on (key, value)')
-        self.assertCountEqual(traverse_obj(_TEST_DATA, lambda _, x: isinstance(x[0], str)), {'str'},
-                              msg='exceptions in the query function should be catched')
-        self.assertEqual(traverse_obj(iter(range(4)), lambda _, x: x % 2 == 0), [0, 2],
-                         msg='function key should accept iterables')
-        if __debug__:
-            with self.assertRaises(Exception, msg='Wrong function signature should raise in debug'):
-                traverse_obj(_TEST_DATA, lambda a: ...)
-            with self.assertRaises(Exception, msg='Wrong function signature should raise in debug'):
-                traverse_obj(_TEST_DATA, lambda a, b, c: ...)
-
-        # Test set as key (transformation/type, like `expected_type`)
-        self.assertEqual(traverse_obj(_TEST_DATA, (..., {str.upper}, )), ['STR'],
-                         msg='Function in set should be a transformation')
-        self.assertEqual(traverse_obj(_TEST_DATA, (..., {str})), ['str'],
-                         msg='Type in set should be a type filter')
-        self.assertEqual(traverse_obj(_TEST_DATA, {dict}), _TEST_DATA,
-                         msg='A single set should be wrapped into a path')
-        self.assertEqual(traverse_obj(_TEST_DATA, (..., {str.upper})), ['STR'],
-                         msg='Transformation function should not raise')
-        self.assertEqual(traverse_obj(_TEST_DATA, (..., {str_or_none})),
-                         [item for item in map(str_or_none, _TEST_DATA.values()) if item is not None],
-                         msg='Function in set should be a transformation')
-        self.assertEqual(traverse_obj(_TEST_DATA, ('fail', {lambda _: 'const'})), 'const',
-                         msg='Function in set should always be called')
-        if __debug__:
-            with self.assertRaises(Exception, msg='Sets with length != 1 should raise in debug'):
-                traverse_obj(_TEST_DATA, set())
-            with self.assertRaises(Exception, msg='Sets with length != 1 should raise in debug'):
-                traverse_obj(_TEST_DATA, {str.upper, str})
-
-        # Test `slice` as a key
-        _SLICE_DATA = [0, 1, 2, 3, 4]
-        self.assertEqual(traverse_obj(_TEST_DATA, ('dict', slice(1))), None,
-                         msg='slice on a dictionary should not throw')
-        self.assertEqual(traverse_obj(_SLICE_DATA, slice(1)), _SLICE_DATA[:1],
-                         msg='slice key should apply slice to sequence')
-        self.assertEqual(traverse_obj(_SLICE_DATA, slice(1, 2)), _SLICE_DATA[1:2],
-                         msg='slice key should apply slice to sequence')
-        self.assertEqual(traverse_obj(_SLICE_DATA, slice(1, 4, 2)), _SLICE_DATA[1:4:2],
-                         msg='slice key should apply slice to sequence')
-
-        # Test alternative paths
-        self.assertEqual(traverse_obj(_TEST_DATA, 'fail', 'str'), 'str',
-                         msg='multiple `paths` should be treated as alternative paths')
-        self.assertEqual(traverse_obj(_TEST_DATA, 'str', 100), 'str',
-                         msg='alternatives should exit early')
-        self.assertEqual(traverse_obj(_TEST_DATA, 'fail', 'fail'), None,
-                         msg='alternatives should return `default` if exhausted')
-        self.assertEqual(traverse_obj(_TEST_DATA, (..., 'fail'), 100), 100,
-                         msg='alternatives should track their own branching return')
-        self.assertEqual(traverse_obj(_TEST_DATA, ('dict', ...), ('data', ...)), list(_TEST_DATA['data']),
-                         msg='alternatives on empty objects should search further')
-
-        # Test branch and path nesting
-        self.assertEqual(traverse_obj(_TEST_DATA, ('urls', (3, 0), 'url')), ['https://www.example.com/0'],
-                         msg='tuple as key should be treated as branches')
-        self.assertEqual(traverse_obj(_TEST_DATA, ('urls', [3, 0], 'url')), ['https://www.example.com/0'],
-                         msg='list as key should be treated as branches')
-        self.assertEqual(traverse_obj(_TEST_DATA, ('urls', ((1, 'fail'), (0, 'url')))), ['https://www.example.com/0'],
-                         msg='double nesting in path should be treated as paths')
-        self.assertEqual(traverse_obj(['0', [1, 2]], [(0, 1), 0]), [1],
-                         msg='do not fail early on branching')
-        self.assertCountEqual(traverse_obj(_TEST_DATA, ('urls', ((1, ('fail', 'url')), (0, 'url')))),
-                              ['https://www.example.com/0', 'https://www.example.com/1'],
-                              msg='tripple nesting in path should be treated as branches')
-        self.assertEqual(traverse_obj(_TEST_DATA, ('urls', ('fail', (..., 'url')))),
-                         ['https://www.example.com/0', 'https://www.example.com/1'],
-                         msg='ellipsis as branch path start gets flattened')
-
-        # Test dictionary as key
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: 100, 1: 1.2}), {0: 100, 1: 1.2},
-                         msg='dict key should result in a dict with the same keys')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: ('urls', 0, 'url')}),
-                         {0: 'https://www.example.com/0'},
-                         msg='dict key should allow paths')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: ('urls', (3, 0), 'url')}),
-                         {0: ['https://www.example.com/0']},
-                         msg='tuple in dict path should be treated as branches')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: ('urls', ((1, 'fail'), (0, 'url')))}),
-                         {0: ['https://www.example.com/0']},
-                         msg='double nesting in dict path should be treated as paths')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: ('urls', ((1, ('fail', 'url')), (0, 'url')))}),
-                         {0: ['https://www.example.com/1', 'https://www.example.com/0']},
-                         msg='tripple nesting in dict path should be treated as branches')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: 'fail'}), {},
-                         msg='remove `None` values when top level dict key fails')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: 'fail'}, default=...), {0: ...},
-                         msg='use `default` if key fails and `default`')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: 'dict'}), {},
-                         msg='remove empty values when dict key')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: 'dict'}, default=...), {0: ...},
-                         msg='use `default` when dict key and `default`')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: {0: 'fail'}}), {},
-                         msg='remove empty values when nested dict key fails')
-        self.assertEqual(traverse_obj(None, {0: 'fail'}), {},
-                         msg='default to dict if pruned')
-        self.assertEqual(traverse_obj(None, {0: 'fail'}, default=...), {0: ...},
-                         msg='default to dict if pruned and default is given')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: {0: 'fail'}}, default=...), {0: {0: ...}},
-                         msg='use nested `default` when nested dict key fails and `default`')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: ('dict', ...)}), {},
-                         msg='remove key if branch in dict key not successful')
-
-        # Testing default parameter behavior
-        _DEFAULT_DATA = {'None': None, 'int': 0, 'list': []}
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, 'fail'), None,
-                         msg='default value should be `None`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, 'fail', 'fail', default=...), ...,
-                         msg='chained fails should result in default')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, 'None', 'int'), 0,
-                         msg='should not short cirquit on `None`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, 'fail', default=1), 1,
-                         msg='invalid dict key should result in `default`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, 'None', default=1), 1,
-                         msg='`None` is a deliberate sentinel and should become `default`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, ('list', 10)), None,
-                         msg='`IndexError` should result in `default`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, (..., 'fail'), default=1), 1,
-                         msg='if branched but not successful return `default` if defined, not `[]`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, (..., 'fail'), default=None), None,
-                         msg='if branched but not successful return `default` even if `default` is `None`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, (..., 'fail')), [],
-                         msg='if branched but not successful return `[]`, not `default`')
-        self.assertEqual(traverse_obj(_DEFAULT_DATA, ('list', ...)), [],
-                         msg='if branched but object is empty return `[]`, not `default`')
-        self.assertEqual(traverse_obj(None, ...), [],
-                         msg='if branched but object is `None` return `[]`, not `default`')
-        self.assertEqual(traverse_obj({0: None}, (0, ...)), [],
-                         msg='if branched but state is `None` return `[]`, not `default`')
-
-        branching_paths = [
-            ('fail', ...),
-            (..., 'fail'),
-            100 * ('fail',) + (...,),
-            (...,) + 100 * ('fail',),
-        ]
-        for branching_path in branching_paths:
-            self.assertEqual(traverse_obj({}, branching_path), [],
-                             msg='if branched but state is `None`, return `[]` (not `default`)')
-            self.assertEqual(traverse_obj({}, 'fail', branching_path), [],
-                             msg='if branching in last alternative and previous did not match, return `[]` (not `default`)')
-            self.assertEqual(traverse_obj({0: 'x'}, 0, branching_path), 'x',
-                             msg='if branching in last alternative and previous did match, return single value')
-            self.assertEqual(traverse_obj({0: 'x'}, branching_path, 0), 'x',
-                             msg='if branching in first alternative and non-branching path does match, return single value')
-            self.assertEqual(traverse_obj({}, branching_path, 'fail'), None,
-                             msg='if branching in first alternative and non-branching path does not match, return `default`')
-
-        # Testing expected_type behavior
-        _EXPECTED_TYPE_DATA = {'str': 'str', 'int': 0}
-        self.assertEqual(traverse_obj(_EXPECTED_TYPE_DATA, 'str', expected_type=str),
-                         'str', msg='accept matching `expected_type` type')
-        self.assertEqual(traverse_obj(_EXPECTED_TYPE_DATA, 'str', expected_type=int),
-                         None, msg='reject non matching `expected_type` type')
-        self.assertEqual(traverse_obj(_EXPECTED_TYPE_DATA, 'int', expected_type=lambda x: str(x)),
-                         '0', msg='transform type using type function')
-        self.assertEqual(traverse_obj(_EXPECTED_TYPE_DATA, 'str', expected_type=lambda _: 1 / 0),
-                         None, msg='wrap expected_type fuction in try_call')
-        self.assertEqual(traverse_obj(_EXPECTED_TYPE_DATA, ..., expected_type=str),
-                         ['str'], msg='eliminate items that expected_type fails on')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: 100, 1: 1.2}, expected_type=int),
-                         {0: 100}, msg='type as expected_type should filter dict values')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: 100, 1: 1.2, 2: 'None'}, expected_type=str_or_none),
-                         {0: '100', 1: '1.2'}, msg='function as expected_type should transform dict values')
-        self.assertEqual(traverse_obj(_TEST_DATA, ({0: 1.2}, 0, {int_or_none}), expected_type=int),
-                         1, msg='expected_type should not filter non final dict values')
-        self.assertEqual(traverse_obj(_TEST_DATA, {0: {0: 100, 1: 'str'}}, expected_type=int),
-                         {0: {0: 100}}, msg='expected_type should transform deep dict values')
-        self.assertEqual(traverse_obj(_TEST_DATA, [({0: '...'}, {0: '...'})], expected_type=type(...)),
-                         [{0: ...}, {0: ...}], msg='expected_type should transform branched dict values')
-        self.assertEqual(traverse_obj({1: {3: 4}}, [(1, 2), 3], expected_type=int),
-                         [4], msg='expected_type regression for type matching in tuple branching')
-        self.assertEqual(traverse_obj(_TEST_DATA, ['data', ...], expected_type=int),
-                         [], msg='expected_type regression for type matching in dict result')
-
-        # Test get_all behavior
-        _GET_ALL_DATA = {'key': [0, 1, 2]}
-        self.assertEqual(traverse_obj(_GET_ALL_DATA, ('key', ...), get_all=False), 0,
-                         msg='if not `get_all`, return only first matching value')
-        self.assertEqual(traverse_obj(_GET_ALL_DATA, ..., get_all=False), [0, 1, 2],
-                         msg='do not overflatten if not `get_all`')
-
-        # Test casesense behavior
-        _CASESENSE_DATA = {
-            'KeY': 'value0',
-            0: {
-                'KeY': 'value1',
-                0: {'KeY': 'value2'},
-            },
-        }
-        self.assertEqual(traverse_obj(_CASESENSE_DATA, 'key'), None,
-                         msg='dict keys should be case sensitive unless `casesense`')
-        self.assertEqual(traverse_obj(_CASESENSE_DATA, 'keY',
-                                      casesense=False), 'value0',
-                         msg='allow non matching key case if `casesense`')
-        self.assertEqual(traverse_obj(_CASESENSE_DATA, (0, ('keY',)),
-                                      casesense=False), ['value1'],
-                         msg='allow non matching key case in branch if `casesense`')
-        self.assertEqual(traverse_obj(_CASESENSE_DATA, (0, ((0, 'keY'),)),
-                                      casesense=False), ['value2'],
-                         msg='allow non matching key case in branch path if `casesense`')
-
-        # Test traverse_string behavior
-        _TRAVERSE_STRING_DATA = {'str': 'str', 1.2: 1.2}
-        self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, ('str', 0)), None,
-                         msg='do not traverse into string if not `traverse_string`')
-        self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, ('str', 0),
-                                      traverse_string=True), 's',
-                         msg='traverse into string if `traverse_string`')
-        self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, (1.2, 1),
-                                      traverse_string=True), '.',
-                         msg='traverse into converted data if `traverse_string`')
-        self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, ('str', ...),
-                                      traverse_string=True), 'str',
-                         msg='`...` should result in string (same value) if `traverse_string`')
-        self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, ('str', slice(0, None, 2)),
-                                      traverse_string=True), 'sr',
-                         msg='`slice` should result in string if `traverse_string`')
-        self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, ('str', lambda i, v: i or v == "s"),
-                                      traverse_string=True), 'str',
-                         msg='function should result in string if `traverse_string`')
-        self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, ('str', (0, 2)),
-                                      traverse_string=True), ['s', 'r'],
-                         msg='branching should result in list if `traverse_string`')
-        self.assertEqual(traverse_obj({}, (0, ...), traverse_string=True), [],
-                         msg='branching should result in list if `traverse_string`')
-        self.assertEqual(traverse_obj({}, (0, lambda x, y: True), traverse_string=True), [],
-                         msg='branching should result in list if `traverse_string`')
-        self.assertEqual(traverse_obj({}, (0, slice(1)), traverse_string=True), [],
-                         msg='branching should result in list if `traverse_string`')
-
-        # Test re.Match as input obj
-        mobj = re.fullmatch(r'0(12)(?P<group>3)(4)?', '0123')
-        self.assertEqual(traverse_obj(mobj, ...), [x for x in mobj.groups() if x is not None],
-                         msg='`...` on a `re.Match` should give its `groups()`')
-        self.assertEqual(traverse_obj(mobj, lambda k, _: k in (0, 2)), ['0123', '3'],
-                         msg='function on a `re.Match` should give groupno, value starting at 0')
-        self.assertEqual(traverse_obj(mobj, 'group'), '3',
-                         msg='str key on a `re.Match` should give group with that name')
-        self.assertEqual(traverse_obj(mobj, 2), '3',
-                         msg='int key on a `re.Match` should give group with that name')
-        self.assertEqual(traverse_obj(mobj, 'gRoUp', casesense=False), '3',
-                         msg='str key on a `re.Match` should respect casesense')
-        self.assertEqual(traverse_obj(mobj, 'fail'), None,
-                         msg='failing str key on a `re.Match` should return `default`')
-        self.assertEqual(traverse_obj(mobj, 'gRoUpS', casesense=False), None,
-                         msg='failing str key on a `re.Match` should return `default`')
-        self.assertEqual(traverse_obj(mobj, 8), None,
-                         msg='failing int key on a `re.Match` should return `default`')
-        self.assertEqual(traverse_obj(mobj, lambda k, _: k in (0, 'group')), ['0123', '3'],
-                         msg='function on a `re.Match` should give group name as well')
-
-        # Test xml.etree.ElementTree.Element as input obj
-        etree = xml.etree.ElementTree.fromstring('''<?xml version="1.0"?>
-        <data>
-            <country name="Liechtenstein">
-                <rank>1</rank>
-                <year>2008</year>
-                <gdppc>141100</gdppc>
-                <neighbor name="Austria" direction="E"/>
-                <neighbor name="Switzerland" direction="W"/>
-            </country>
-            <country name="Singapore">
-                <rank>4</rank>
-                <year>2011</year>
-                <gdppc>59900</gdppc>
-                <neighbor name="Malaysia" direction="N"/>
-            </country>
-            <country name="Panama">
-                <rank>68</rank>
-                <year>2011</year>
-                <gdppc>13600</gdppc>
-                <neighbor name="Costa Rica" direction="W"/>
-                <neighbor name="Colombia" direction="E"/>
-            </country>
-        </data>''')
-        self.assertEqual(traverse_obj(etree, ''), etree,
-                         msg='empty str key should return the element itself')
-        self.assertEqual(traverse_obj(etree, 'country'), list(etree),
-                         msg='str key should lead all children with that tag name')
-        self.assertEqual(traverse_obj(etree, ...), list(etree),
-                         msg='`...` as key should return all children')
-        self.assertEqual(traverse_obj(etree, lambda _, x: x[0].text == '4'), [etree[1]],
-                         msg='function as key should get element as value')
-        self.assertEqual(traverse_obj(etree, lambda i, _: i == 1), [etree[1]],
-                         msg='function as key should get index as key')
-        self.assertEqual(traverse_obj(etree, 0), etree[0],
-                         msg='int key should return the nth child')
-        self.assertEqual(traverse_obj(etree, './/neighbor/@name'),
-                         ['Austria', 'Switzerland', 'Malaysia', 'Costa Rica', 'Colombia'],
-                         msg='`@<attribute>` at end of path should give that attribute')
-        self.assertEqual(traverse_obj(etree, '//neighbor/@fail'), [None, None, None, None, None],
-                         msg='`@<nonexistant>` at end of path should give `None`')
-        self.assertEqual(traverse_obj(etree, ('//neighbor/@', 2)), {'name': 'Malaysia', 'direction': 'N'},
-                         msg='`@` should give the full attribute dict')
-        self.assertEqual(traverse_obj(etree, '//year/text()'), ['2008', '2011', '2011'],
-                         msg='`text()` at end of path should give the inner text')
-        self.assertEqual(traverse_obj(etree, '//*[@direction]/@direction'), ['E', 'W', 'N', 'W', 'E'],
-                         msg='full Python xpath features should be supported')
-        self.assertEqual(traverse_obj(etree, (0, '@name')), 'Liechtenstein',
-                         msg='special transformations should act on current element')
-        self.assertEqual(traverse_obj(etree, ('country', 0, ..., 'text()', {int_or_none})), [1, 2008, 141100],
-                         msg='special transformations should act on current element')
-
     def test_http_header_dict(self):
         headers = HTTPHeaderDict()
         headers['ytdl-test'] = b'0'